Satellite Collision Avoidence Methods Questioned

[ozone]

RE: The Iridium Collision

http://www.space.com/news/090227-space-collision-questions.html

 

[Urwumpe]

RE: The Iridium Collision

http://www.space.com/news/090227-space-collision-questions.html

This is stupid. Just changing the orbit period by 0.1 seconds means a huge distance to your threatened position over 24-48 hours. You just need to react. In which direction you react, is not too important.

 

[tblaxland]

This is stupid. Just changing the orbit period by 0.1 seconds means a huge distance to your threatened position over 24-48 hours. You just need to react. In which direction you react, is not too important.

I think the important point from the article was that you need to know that you need to react. From what I've heard on this forum, Iridium was given a warning, despite their claims to the contrary in that article.

 

[agentgonzo]

I think the important point from the article was that you need to know that you need to react. From what I've heard on this forum, Iridium was given a warning, despite their claims to the contrary in that article.

Stuff on the forum may have been conjecture. If a reputable news agency reported that they didn't have a warning, then I'd assume they didn't

 

[garyw]

Stuff on the forum may have been conjecture. If a reputable news agency reported that they didn't have a warning, then I'd assume they didn't

I'd disagree. It's quite likely that the company are trying to hide a major mistake.

I can easily envisage a scenario where Norad phone up to say "Hey, your Iridium satellite will get side swiped by Russian Cosmos sat in two days unless you do a CAM" and the person on the other end of the phone goes "Sure... Nice joke!"

BAM. No joke.

 

[SiberianTiger]

http://www.ottawacitizen.com/techno...tellite+crash+company+says/1282332/story.html

Iridium had been receiving a weekly average of 400 conjunction reports from the U.S. Strategic Command’s Joint Space Operations Center that tracks debris in space, Gen. Campbell told a June, 2007, forum hosted by the George C. Marshall Institute, a Washington research group.


“So the ability actually to do anything with all the information is pretty limited,” he said, describing a kind of data overload. The conjunction reports were issued every time a potential threat object was to pass within five kilometers of a commercial satellite, he said.


“Even if we had a report of an impending direct collision, the error would be such that we might maneuver into a collision as well as move away from one,” he told the panel.


Gen. Campbell then endorsed the so-called “Big Sky” theory -- that space is so vast that the chances of a collision are infinitesimal, despite more than 18,000 pieces of orbiting junk big enough to track.

 

[tblaxland]

Stuff on the forum may have been conjecture. If a reputable news agency reported that they didn't have a warning, then I'd assume they didn't

Maybe:
http://www.orbiter-forum.com/showthread.php?p=79605#post79605

Or maybe these warnings are so common they just get ignored, per ST's post.

 

[Urwumpe]

400 possible warnings per week is not too much, for speaking about data overload (especially if you operate 66 satellites). Imagine a doctor complaining about having 400 patients every week.

400 warnings per week are less than 6 warnings per satellite per week. You would on the average deal with one collision warning per day, for one satellite.

The space debris warning are part of normal everyday operations and if you don't have the employees, to deal with them, you leave a very bad image of your performance. Blaming the USSSN for not being accurate enough with their warnings, is stupid. The USSSN watches a few thousand objects in Earth orbit and you can be lucky that they issue such warnings to you, instead of you being forced to watch for your investment by analysis the TLEs of all dangerous objects.

After all, it is just like in Air Traffic. If a ATC issues a collision warning based on his rough radar data, this does not mean that there is a dire collision risk. But you need to deal with it, look at your own state and do the decisions that are required. This does not always mean that following the ATC is the best way (look at the Bodensee collision), but their recommendations have weight unless you really know better.

Sorry, but I don't accept this kind of excuse. If the USSSN already reduces the work load for you, by issueing such warnings and do the calculations for you, you should not complain about a too high workload.

If satellite operators want better service... they can buy it. Either by employing their own engineers for this task, or by contracting a special company for such analysis. I am pretty sure such experts exist not only inside CNES and the rest of ESA.

I would estimate, that if you can get accurate state vectors from the satellite operators and other information (propellant resources, for example), you could deal with the 400 warnings every week with about 5-8 engineers, who do nothing else but that.

 

[Ghostrider]

Imagine a doctor complaining about having 400 patients every week.

I don't have to imagine too much...

400 patients a week? Over your dead body.

 

[garyw]

After all, it is just like in Air Traffic. If a ATC issues a collision warning based on his rough radar data, this does not mean that there is a dire collision risk. But you need to deal with it, look at your own state and do the decisions that are required. This does not always mean that following the ATC is the best way (look at the Bodensee collision), but their recommendations have weight unless you really know better.

Maybe satellites need their own version of TCAS?

 

[SiberianTiger]

Maybe satellites need their own version of TCAS?

And the dead ones too?

 

[Urwumpe]

Maybe satellites need their own version of TCAS?

Would not work economic. You would need far longer reaching transponders in space, requiring more electrical power. 50 km distance in space, would just buy you 3-4 seconds to estimate the collision risk and evade.

 

[garyw]

Ok, so 2 small flaws in an otherwise perfect plan.... I've had worse!

 

[Urwumpe]

Ok, so 2 small flaws in an otherwise perfect plan.... I've had worse!

Don't tell me you thought about installing ASAT MKVs on spacecraft as final defense.

I think the best solution would be all commercial satellite operators (and maybe the governmental as well) join in a Organization of the SunSync Orbit Satellite Operators. OSSOSO... sounds like a deadly acronym for anchormen.

If they then exchange information about their orbits and have a common task force for dealing with collision warnings, this could improve workflow a lot.

 

[Zatnikitelman]

Or what about more accurate radar measurements? Could a commercial contractor (SpaceX?) launch a series of active-radar satellites that monitor debris from orbit and it be more effective (and not classified!) that what's publicly available.

 

[Urwumpe]

Or what about more accurate radar measurements? Could a commercial contractor (SpaceX?) launch a series of active-radar satellites that monitor debris from orbit and it be more effective (and not classified!) that what's publicly available.

How could you do this more accurate than the stuff used also for ballistic missile defense? The ESA plans for more accurate radar stations in Europe is already massive, regardless the fact that it will never, under no circumstances, become comparable to the US system. We just can't afford it.

 

[T.Neo]

Do ISS/Shuttle have their own collision radar?

How feasible is this?

I'd find it interesting for at least ISS.

 

[SiberianTiger]

Do ISS/Shuttle have their own collision radar?

How feasible is this?

I'd find it interesting for at least ISS.

No, they don't. Their collision avoidance ability is completely up to mt. Cheyenne / Krasnoznamensk.

 

[garyw]

ISS and Shuttle have a "box" of protection where they will perform a collision avoidance maneuver if anything enters that box.

On another note, How practical (computing power wise) would it be to simulate all objects in LEO and predict collisions based on an approach of 1km? 500metres?

Is this something that satellite companies should now be investing in?

 

[Ghostrider]

Is this something that satellite companies should now be investing in?

Why should they? If their birds are insured, they don't need to care. If they don't have the money to insure them, then they don't have the money to invest in a space-tracking program.